ablutions vs bathtub

ablutions

noun
  • The location or building where the showers and basins are located. 

  • A building that houses bathing and toilet facilities on a military base. 

bathtub

noun
  • A large container for holding water in which a person may bathe (take a bath). 

How often have the words ablutions and bathtub occurred in a corpus of books? (source: Google Ngram Viewer )